1. Field of the Invention
The present invention relates to an ESD protection device.
2. Description of the Related Art
An ESD protection device is described in International Publication No. WO2011/040435. The ESD protection device includes a ceramic element assembly containing a glass component, a first discharge electrode and a second discharge electrode that are disposed in the ceramic element assembly and that oppose each other with a gap therebetween, a discharge auxiliary electrode that connects the first discharge electrode to the second discharge electrode, and a seal layer that suppresses a glass component in the ceramic element assembly from entering the discharge auxiliary electrode.
Incidentally, regarding the ESD protection device in the related art, in order to decrease a discharge starting voltage, the gap between the first discharge electrode and the second discharge electrode has to be reduced or the conductive component in the discharge auxiliary electrode has to be increased. However, these configurations have a problem of degraded insulation quality.
In addition, the seal layer is composed of alumina and, as a result, the degree of shrinkage is low compared to the ceramic element assembly. Therefore, a difference in shrinkage between the ceramic element assembly and the seal layer increases during firing of the ceramic element assembly, and a defect in the ceramic element assembly may occur.